High voltage/high current air break switches typically include an elongated conductive contact or “blade” that engages an electrical terminal to establish an electrical connection. Depending on the voltage difference between the blade and the electrical terminal, electrical arcing can occur and potentially damage contact surfaces of the blade and the electrical terminal if the blade moves slightly out of contact with the terminal. As such, some previous air break switch designs locked or otherwise secured the blade to the electrical terminal during operation to inhibit arcing. With some of these designs, the locking components applied relatively large holding forces on the blade, and these large forces needed to be overcome to properly engage the blade with the electrical terminal.
To address the drawbacks of these high-locking force designs, other previous designs included blades that could be closed by exerting relatively low forces. With some of these designs, rotating an operating mechanism (e.g., and elongated shaft extending to the ground) would first cause the blade to pivot about a vertical axis and enter the electrical terminal. Continued rotation of the operating mechanism would then pivot the blade about its longitudinal axis and move the contact surfaces into engagement with the electrical terminal.
However, it can be difficult for an operator standing on the ground to observe longitudinal rotation of the blade even if the switch is mounted at a relatively low height on a utility structure. As such, it can be difficult to determine if the blade has established a proper electrical connection with the electrical terminal. If the blade does not properly engage the electrical terminal, potentially-damaging arcing can occur as described above.
Considering the drawbacks of previous designs, a need exists for an improved air break switch that indicates whether a pivotable blade is in an open or closed position.